First off, the sidewall differentiation you are seeing in the Toyo Open Country ATs is due to the difference in sidewall design between the 6 ply passenger tire, like on SUVs, and the 10 ply light truck tire. The light truck tire has a more tread wrap than the SUV tire, to protect the sidewall during off-road use. The Toyo's are an excellent tire, and as an independent tire dealer, comprise the majority of my sales. I also sell Remington, Dunlop, Cooper, BFG, Michelin, Summit, Mastercraft, and General. The Toyo's are what's on my wife's kid mobile. I have MT's on her '97 Dodge 2500 4x4. I don't think the MTs are any quieter on the road than most other like-treaded tires, but they do tend to run a long time. I sold several sets to one guy in 285-75R16, and he's gotten 60 and 65k out of each of the last two sets. I also own and operate a number of ranches in Texas, one reason I'm a tire dealer. I run offroad a LOT. More than most. Most tires I replace due to external damage from terrain or debris, such as Mesquite stumps or oak stobs. The TOYO ATs replaced all other sets of tires on my ranch hand's trucks, as tire problems reduced by almost half. That tells me they are tougher than the others. I run some other tires in other applications just to stay up with the market, and when I capitalize on closeouts and specials. The General AT2 and Remington Mud Brutes tend to be good tires, but the Remington's have no longetivity, mileage wise. The one current set of Dick Cepeck's I have in service appear to not be as good the Toyo's. They are having a lot of flats and I have had one tread separation. The tread design is decent, but the carcass appears to be of Goodyear mold(ProComp, Mickey Thompson, Dick Cepeck, Kelly, Ridge Runner: all made under Goodyear roof), and those tires have consistently not held up to the abuse I put them under. Tread separation was common, and often with less than 20k miles on them. Nitto's have held up well, but my test pool has been shallow.
Secondly,
How accurate is your speedometer to begin with? Most trucks I check or have run on the dyno have been either 1. 5 to 3. 5 mph faster than actual speed. Adding 285/75R17s to a truck with the speedometer running 3. 5 mph slow, will make it close to being on. A 285 is 33. 8 inches in Dia, while a 265/70R17 is 31. 6in diam. Roll out is not much further apart, and over the life of the tires will only amount to about 100 miles..... Just something to think about. I'm all for less RPM's and run 35's on just about everthing I can. Just some info for your consideration...
Good luck,
God bless,
Casey